Method of decorating items of jewellery

ABSTRACT

A method of decorating items of jewelry. The method includes the steps of bringing about a translational relative movement between the item and a cutting tool along the longitudinal axis of the item, and driving the tool with a cutting movement in contact with the surface thereof, along preselected cutting paths, in order to produce corresponding decorative marks on the surface. The method further includes the step of providing a support for the item, the support being rotatable about an axis extending along the axis of the relative translation between the tool and the item so that the tool is driven in contact with the surface during the combined and simultaneous rotary and translational movement of the item.

TECHNICAL FIELD

[0001] The present invention relates to a method of decorating items of jewellery according to the preamble to main claim 1.

[0002] The invention is also directed towards an item produced in accordance with the above-mentioned method, as well as towards a machine for implementing the method.

TECHNOLOGICAL BACKGROUND

[0003] In the technical field of the production of chains for items of jewellery, and in the goldsmithery field in particular, it is known to provide decorations on the surface of the chain, for example, by means of one or more marks engraved with a cutting tool such as a diamond cutter. Decorations of different geometrical configurations and aesthetic effects can be produced in dependence on the preselected speed of relative translational movement between the chain and the tool, as well as on the cutting movement of the tool itself.

[0004] This method is used effectively for all chains with so-called flat links, that is, chains in which the rectilinear profile of the surface of the chain to be decorated enables diamond engraving to be produced over the entire surface as a result of the relative translational movement between the tool and the chain.

[0005] However, if the chain has a surface with a curved profile, the known method has clear limitations since the cutting movement of the tool enables the surface to be engraved only partially and cannot therefore be used when a decoration extending over the entire curved profile of the surface is required. This situation arises, for example, in items of jewellery formed by chains known in the art by the term “OMEGA-shaped chains”, which have outer surfaces having convex curved profiles.

DESCRIPTION OF THE INVENTION

[0006] The technical problem upon which the present invention is based is that of providing a method of decorating items of jewellery which is designed to overcome the limitations discussed with reference to the prior art mentioned.

[0007] This problem is solved by the invention by a method of decorating, items of jewellery according to the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The characteristics and; the advantages of the invention will become clearer from the following detailed description of an embodiment thereof, given by way of non-limiting example, with reference to the appended drawings, in which;

[0009]FIG. 1 is a partial perspective view showing, on an enlarged scale, a chain for items of jewellery formed in accordance with the method of the invention,

[0010]FIG. 2 is a partial schematic view of a machine operating by the method of the invention,

[0011]FIG. 3 is a front elevational view showing a detail of FIG. 2, on an enlarged scale,

[0012]FIG. 4 is a partially-sectioned plan view of a further detail of FIG. 2,

[0013]FIG. 5 is a view, corresponding to that of FIG. 2, of a machine operating in accordance with a variant of the method of the invention,

[0014]FIG. 6 is a partial plan view of an item of jewellery decorated in accordance with the variant of the method of FIG. 5,

[0015]FIG. 7 is a perspective view showing, on an enlarged scale, a detail of the machine of FIG. 5 operating in accordance with the variant of the abovementioned method, and

[0016]FIG. 8 is an exploded, perspective view of the detail of FIG. 7.

PREFERRED METHOD OF IMPLEMENTING THE INVENTION

[0017] With reference initially to FIG. 1, an item of jewellery, extending along a predominant longitudinal axis and formed as a spiral chain, is generally indicated 1 and comprises a plurality of links 2 formed in accordance with the method of the present invention and designed for the production of necklaces, bracelets and the like.

[0018] The chain 1, which is also known in the goldsmithery field as an OMEGA-shaped chain, is preferably produced by winding a ribbon-like body with a curved profile on a central core 2 a to define the links 2 adjacent one another. The chain has a lower surface 3 adjoining an opposed convex curved surface 4 which constitutes the portion that is normally visible when the chain is worn.

[0019] The chain also has, on its surface 4, a decoration constituted by a plurality of marks, all indicated 5, which are engraved by means of a cutting, tool 6 and are arranged in accordance with a preselected geometrical configuration produced by the method described in detail below.

[0020] The tool 6 is preferably a diamond cutter mounted on a tool-holder element 6 a, shown only schematically in FIG. 2.

[0021] The method provides for a translational relative movement to be brought about between the chain 1 and the tool 6, along the longitudinal axis of the chain, indicated by the axis X of FIG. 2. In particular, the chain 1 is arranged to be pulled along the axis X, relative to the tool; 6, by pulling means, for example, comprising pairs of contrarotating rollers 7 between which the chain is drawn along by friction (FIG. 2).

[0022] The method also provides for the arrangement of a chain-holder support 8 in which there is a slot 9 for housing a portion of chain. The support 8 has a cylindrical shape with a circular cross-section such that the curved profile of the chain surface extends so as to be superimposed substantially on the circumferential profile of the cross-section of the support, as shown in FIG. 3. This characteristic is achieved by the use of a radius of curvature for the circular cross-section of the support which is the same as that of the curved profile of the chain surface.

[0023] According to the method of the invention, the chain-holder support 8 is housed rotatably in a seat 10 of a housing 11 and can oscillate about its axis X′ of axial symmetry which extends parallel to the direction of the axis X. The oscillatory movement is brought about by means of a pivoting device 12 (shown schematically in FIG. 2) connected to the support 8 by means of a rod-like appendage 13.

[0024] The tool 6 is brought into contact with the surface 4 of the chain through an opening 14 formed in the housing 11. A plurality of recesses 15, inclined to the axis X at different angles, is formed in the housing 11, in the region of the opening 14, for the guided insertion of the tool 6 along preselected axes which are inclined to one another.

[0025] According to the method of the invention, the chain is thus subjected, simultaneously, to a translational movement along the axis X and to an oscillatory movement about the axis X′, so that the entire curved surface is presented in the opening 14 and is in turn engraved by the cutting tool 6.

[0026] By virtue of the combined and simultaneous translational and oscillatory movements, the decoration by surface engraving can thus be formed on the entire curved surface of the chain, as shown in FIG. 1.

[0027] The cutting operation by the tool, which is performed, for example, by means of a diamond cutter, is also arranged to be of the discontinuous type.

[0028] Moreover, by virtue of the presence of the recesses 15, the tool can be guided in its contact with the surface along axes which are inclined to the axis X, thus producing marks of different inclinations, for example, in order to produce star-shaped decorative patterns.

[0029] In dependence on the speed of translation and oscillation of the chain and of the support, as well as on the inclination of the tool to the longitudinal axis of the chain, it is possible to produce decorations by diamond engraving of the surface in accordance with preselected and different geometrical configurations of excellent aesthetic effect.

[0030] The method of the invention is intended to be applicable effectively to any chain or other item of jewellery with a curved surface which requires surface decoration extending along part or all of its outer curved surface.

[0031] In a variant of the method of the invention, described with particular reference to FIGS. 5 to 8, in which details similar to those of the preceding embodiment are indicated by the same reference numerals, the decorations by diamond engraving of the above-mentioned type are produced on an item of jewellery 20 of tubular shape with a substantially cylindrical cross-section. This tubular structure is also known as a “gas-pipe” structure.

[0032] The item 20, otherwise defined below as the tubular chain, has a plurality of adjacent annular portions 21 with substantially cylindrical outer curved surfaces 21 a. Each tubular portion 21 has, on the corresponding curved surface 21 a, a decoration constituted by marks 5 engraved by means of the tool 6 and arranged in accordance with a preselected geometrical configuration.

[0033] This variant of the invention differs from the preceding, embodiment mainly in that the tubular chain is driven with rotary movement about its longitudinal axis, indicated X″ in FIG. 5, in addition to its translational movement relative to the tool. For this purpose, a through-hole 22, extending along the axis X″, is provided the housing 11 for housing the tubular chain 20 rotatably with limited radial clearance.

[0034] A core, indicated 23, for example, of plastics material such as nylon, can be inserted in the tubular cavity of the chain 20 in order to afford it sufficient stiffness during the decoration steps performed by the method of the invention.

[0035] The pairs of contrarotating rollers 7 have annular grooves 24 for partially housing the curved surface of the chain and consequently pulling it along by friction in its translational movement along the axis X″. Each pair of rollers 7 is also mounted on a respective support 25 (shown schematically in the drawing) rotating about the axis X″ so that the chain is subjected simultaneously to a translational movement along the axis X and to a rotational movement about the axis X″ (for example, in the direction of the arrow A of FIG. 5), the entire cylindrical surface thus being presented in the opening 14 and therefore being engraved by the cutting tool 6.

[0036] The housing 11 is preferably formed in two structurally independent parts; 11 a, 11 b, each having a half-hole 22 a, 22 b so that, when the parts are connected to one another, for example, by screw means, they jointly define the hole 22.

[0037] Pressing means are also provided and are positioned in the housing 11 in the region of the opening 14, for pressing the tubular chain against the inner surface of the hole 22 in opposition to the cutting forces exerted by the tool, to ensure adequate accuracy in the diamond-engraving of the chain.

[0038] The pressing means comprise a jack-like device 26, for example, a pneumatic device the rod of which extends through a hole 27 which is formed in the housing 11 and in turn communicates with a cavity 28 opening into the hole 22. A block-like element 29 is advantageously housed in the cavity 28 in a position between the pressing means and the chain for improved distribution of the pressure exerted on the curved surface of the tubular chain. As an alternative to the jack 26, the use of a spring or other similar pressing means is envisaged. This system also enables surfaces having considerable dimensional irregularities (even of the order of a few hundredths of a millimetre) to be processed.

[0039] The invention thus solves the problem posed, achieving the advantages mentioned above over known solutions.

[0040] In particular, the invention leads to the main advantage that, by surface diamond engraving over the entire extent of the surfaces of chains having curved surfaces, it is possible to produce decorations which cannot be produced by conventional methods. 

1. A method of decorating an item of jewellery (1; 20) extending along a predominant longitudinal axis, comprising the steps of: bringing about a translational relative movement between the item (1; 20) and a cutting tool (6), along the longitudinal axis of the item, driving the tool (6) with a cutting movement in contact with the surface (4; 21 a) of the item, along preselected cutting paths, in order to produce corresponding decorative marks (15) on the surface of the item, characterized in that it comprises the step of providing support means for the item, the support means being rotatable about an axis (X′; X″) extending in the direction of relative translation between the tool (6) and the item so that the tool is driven in contact with the surface (4; 21 a) during the combined and simultaneous rotary and translational movement of the items.
 2. A method according to claim 1 in which the support means can oscillate about the axis.
 3. A method according to claim 1 or claim 2 in which the item (1; 20) is pulled in its translational movement relative to the tool (6).
 4. A method according to any one of the preceding claims, in which the cutting by the tool (6) is of the discontinuous type.
 5. A method according to claim 4, in which the cutting profile of the tool (6) has an adjustable inclination to the direction of pulling of the item so that decorative marks of preselected and different inclinations to the longitudinal axis of the item are produced on the surface (4′ 21 a) of the item.
 6. A method according to one or more of the preceding claims in which the item (1; 20) has a surface with a curved profile.
 7. A method according to claim 6 in which the item is substantially OMEGA-shaped in cross-section.
 8. A method according to claim 6 in which the item has a tubular shape with a cross-section having a substantially circular profile.
 9. A method according to one or more of the preceding claims in which the cutting operation is a diamond engraving operation.
 10. An item of jewellery with a curved surface produced in accordance with the method of one or more of claims 1 to
 9. 11. An item of jewellery according to claim 10, formed as a chain with a plurality of links adjacent one another.
 12. A machine for decorating items of jewellery operating in accordance with the method of one or more of claims 1 to
 9. 